docs: def format_output(instances, flag):
      """return formatted string per instance"""
      out = []
      line_format = '{0}\t{1}\t{2}\t{3}'
      name_len = _get_max_name_len(instances) + 3
      if flag:
          line_format = '{0:<' + str(name_len+5) + '}{1:<16}{2:<65}{3:<16}'
  
      for i in instances:
          endpoint = "{0}:{1}".format(i['Endpoint']['Address'], i['Endpoint']['Port'])
          out.append(
              line_format.format(i['DBInstanceIdentifier'], i['DBInstanceStatus'], endpoint, i['Engine']))
      return out